This invention relates to valve handle assemblies for manually-operated quarter-turn valves, such as plug valves and ball valves. These valves are ubiquitous in industrial settings such as manufacturing plants, refineries, chemical processing plants, oilfield operations, etc. These uses often control the flow of hazardous substances or substances which, if released, would result in the loss of valuable product or damage to property. Manually-operated quarter-turn valves have the advantage of closing and opening with limited movement required of the valve handle. In addition, the position of the valve handle immediately indicates whether the valve is open or closed. A disadvantage of these valves is that the valves can be inadvertently operated. For example, if such a valve is used to control fluids flowing through a ground level pipeline, it is possible for the handles to be kicked or tripped over by personnel. This is particularly true when the valves in the closed position, such that the handle is sticking out at a ninety degree angle from the valve body and the pipeline. Such inadvertent operation can have disastrous results.
In an effort to prevent such inadvertent operation of these types of valves, various locking mechanisms have been introduced which lock the valve in the open or closed position, such as the device disclosed in U.S. Pat. No. 5,411,048 to Massey. These types of locks generally prevent the inadvertent opening or closing of quarter-turn valves. However, once the handles have been locked in the closed position, the handles present a safety hazard to personnel walking around ground level valves or valves which are located at approximately head level. A valve handle locked in the closed position—with the valve handle sticking out perpendicular to the pipeline—creates a tripping hazard. Because the valve is locked closed, the handle will not give and thus someone accidentally walking into it will almost certainly trip. If the valves are set at head level, a locked valve handle can present a significant risk of injury from someone bumping or falling into it.